上篇博客，当没有权限的用户访问一些资源时，返回的是403错误，403对于用户来说是一个莫名其妙的数字，我们当然要处理成友好的提示。

关于错误处理，翻看了一下Nancy的源码，是这样处理的，见下面地址：

https://github.com/NancyFx/Nancy/blob/master/src/Nancy/ErrorHandling/DefaultStatusCodeHandler.cs

其实Nancy是允许我们采用相同的办法处理，现在把DefaultStatusCodeHandler.cs的源码复制下来，改成我们自己的CustomStatusCode.cs如下，关于详细说明，参考Nancy源码DefaultStatusCodeHandler.cs。

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using  Nancy;
using  Nancy.ErrorHandling;
using  Nancy.ViewEngines;
using  System.Collections.Generic;
using  System.IO;
using  System.Linq;
using  System.Text;
using  Nancy.Responses.Negotiation;
using  Nancy.Extensions;
using  Nancy.IO;
  
namespace  NancySelfHostWeb
{
     public  class  CustomStatusCode: IStatusCodeHandler
     {
         
         private  const  string  DisableErrorTracesTrueMessage =  "Error details are currently disabled. Please set <code>StaticConfiguration.DisableErrorTraces = false;</code> to enable." ;
  
         private  readonly  IDictionary<HttpStatusCode,  string > errorMessages;
         private  readonly  IDictionary<HttpStatusCode,  string > errorPages;
         private  readonly  IResponseNegotiator responseNegotiator;
         private  readonly  HttpStatusCode[] supportedStatusCodes = { HttpStatusCode.Forbidden, HttpStatusCode.NotFound};
  
         public  CustomStatusCode(IResponseNegotiator responseNegotiator)
         {
             this .errorMessages =  new  Dictionary<HttpStatusCode,  string >
             {
                 { HttpStatusCode.Forbidden,  "查看是否有授权！"  },
                 { HttpStatusCode.NotFound,  "找不到你要的资源！"  }
  
             };
             this .errorPages =  new  Dictionary<HttpStatusCode,  string >
             {
                 { HttpStatusCode.Forbidden, LoadResource( "NancySelfHostWeb.403.html" ) },
                 { HttpStatusCode.NotFound, LoadResource( "NancySelfHostWeb.404.html" ) }
  
             };
             this .responseNegotiator = responseNegotiator;
         }
         
         public  bool  HandlesStatusCode(HttpStatusCode statusCode, NancyContext context)
         {
             return  this .supportedStatusCodes.Any(s => s == statusCode);
         }
  
         public  void  Handle(HttpStatusCode statusCode, NancyContext context)
         {
             if  (context.Response !=  null  && context.Response.Contents !=  null  && !ReferenceEquals(context.Response.Contents, Response.NoBody))
             {
                 return ;
             }
             if  (! this .errorMessages.ContainsKey(statusCode) || ! this .errorPages.ContainsKey(statusCode))
             {
                 return ;
             }
             Response existingResponse =  null ;
             if  (context.Response !=  null )
             {
                 existingResponse = context.Response;
             }
             context.NegotiationContext =  new  NegotiationContext();
             var  result =  new  DefaultStatusCodeHandlerResult(statusCode,  this .errorMessages[statusCode], StaticConfiguration.DisableErrorTraces ? DisableErrorTracesTrueMessage : context.GetExceptionDetails());
             try
             {
                 context.Response =  this .responseNegotiator.NegotiateResponse(result, context);
                 context.Response.StatusCode = statusCode;
  
  
                 if  (existingResponse !=  null )
                 {
                     context.Response.ReasonPhrase = existingResponse.ReasonPhrase;
                 }
                 return ;
             }
             catch  (ViewNotFoundException)
             {
             }
             this .ModifyResponse(statusCode, context, result);
         }
  
  
         private  void  ModifyResponse(HttpStatusCode statusCode, NancyContext context, DefaultStatusCodeHandlerResult result)
         {
             if  (context.Response ==  null )
             {
                 context.Response =  new  Response { StatusCode = statusCode };
             }
             var  contents =  this .errorPages[statusCode];
             if  (! string .IsNullOrEmpty(contents))
             {
                 contents = contents.Replace( "[DETAILS]" , result.Details);
             }
             context.Response.ContentType =  "text/html" ;
             context.Response.Contents = s =>
             {
                 using  ( var  writer =  new  StreamWriter( new  UnclosableStreamWrapper(s), Encoding.UTF8))
                 {
                     writer.Write(contents);
                 }
             };
         }
         private  static  string  LoadResource( string  filename)
         {
  
             // 获取当前资源文件
             var  resourceStream =  typeof (CustomStatusCode).Assembly.GetManifestResourceStream( string .Format( "{0}" , filename));
             if  (resourceStream ==  null )
             {
                 return  string .Empty;
             }
             using  ( var  reader =  new  StreamReader(resourceStream))
             {
                 return  reader.ReadToEnd();
             }
         }
         internal  class  DefaultStatusCodeHandlerResult
         {
             public  DefaultStatusCodeHandlerResult(HttpStatusCode statusCode,  string  message,  string  details)
             {
                 this .StatusCode = statusCode;
                 this .Message = message;
                 this .Details = details;
             }
             public  HttpStatusCode StatusCode {  get ;  private  set ; }
             public  string  Message {  get ;  private  set ; }
             public  string  Details {  get ;  private  set ; }
         }
     }
}


这样还可以把Nancy内置的500，404错误改成我们自定义的显示。

 

有时觉得这样太麻烦，可以自大在Module中去判断登录用户是否具有角色，代码如下

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using  Nancy;
using  Nancy.Security;
using  System.Linq;
 
namespace  TestSelfHostWeb.Modules
{
     public  class  IndexModule : NancyModule
     {
         public  IndexModule()
         {
             //开启全局验证
             this .RequiresAuthentication();
             Get[ "/" ] = parameters =>
             {
                 //开启角色验证，只有该角色可以访问本路由
                 //this.RequiresClaims("admin");
 
                 //自己判断登录角色具有权限
                 if  (! this .Context.CurrentUser.Claims.Contains( "admin" ))
                 {
                     return  View[ "error" ]; //定义一个错误页面error.cshtml即可
                 }
 
                 return  View[ "index" ];
             };
         }
     }
}